Identical plasmid AmpC beta-lactamase genes and plasmid types in E. coli isolates from patients and poultry meat in the Netherlands

The increasing prevalence of third-generation cephalosporin-resistant Enterobacteriaceae is a worldwide problem. Recent studies showed that poultry meat and humans share identical Extended-Spectrum Beta-Lactamase genes, plasmid types, and Escherichia coli strain types, suggesting that transmission from poultry meat to humans may occur. The aim of this study was to compare plasmid-encoded Ambler class C beta-lactamase (pAmpC) genes, their plasmids, and bacterial strain types between E. coli isolates from retail chicken meat and clinical isolates in the Netherlands. In total, 98 Dutch retail chicken meat samples and 479 third-generation cephalosporin non-susceptible human clinical E. coli isolates from the same period were screened for pAmpC production. Plasmid typing was performed using PCR-based replicon typing (PBRT). E coli strains were compared using Multi-Locus-Sequence-Typing (MIST). In 12 of 98 chicken meat samples (12%), pAmpC producing E. coli were detected (all bla(CMY-2)). Of the 479 human E. coli, 25 (5.2%) harboured pAmpC genes (bla(CMY-2) n = 22, bla(ACT) n = 2, bla(MIR) n = 1). PBRT showed that 91% of poultry meat isolates harboured bla(CMY-2) on an IncK plasmid, and 9% on an Inch plasmid. Of the human bla(CMY-2) producing isolates, 42% also harboured bla(CMY-2) on an IncK plasmid, and 47% on an Incl1 plasmid. Thus, 68% of human pAmpC producing E. coli have the same AmpC gene (bla(CMY-2)) and plasmid type (Incl1 or IncK) as found in poultry meat. MLST showed one cluster containing one human isolate and three meat isolates, with an IncK plasmid. These findings imply that a foodborne transmission route of bla(CMY-2) harbouring plasmids cannot be excluded and that further evaluation is required. (C) 2013 Elsevier B.V. All rights reserved.